1. I would say culture and production are still king. Now food isn't crap as before.
2. Problem was that Mathemathics was too good to delay, and the path towards it most convenient. Now the strengths are spread out evenly.
3. I plan on doing a guide soon. Basically, you have the same unhappiness types as before (needs, religious, specialists), but now the happiness is origined locally. This is, each city generates happy and unhappy people. Happy people are capped by city size, while unhappy people can be greater than that. Then you have that any happiness empire bonus is distributed among all your cities, in order of appearance. For, example, if you are gaining 6 happiness from luxuries and you have 4 cities, the two first cities gain 2 happiness each one, and the other two cities gain one happiness points each one. City UI has been changed to show happiness more detailed and informative. You also may see what your city shall look like upon growth. Unhappiness reduction buildings have been simplified. Some building still work at a percentage, like walls, but most of them now just remove 1 point of unhappiness, such as the library which removes 1 point of illiteracy the city may have. Unhappiness from specialists is called urbanization and has its own unhappiness reductions. 1 specialist = 1 urbanization unhappiness. Easy.
The food change is just a thoroughly removal of food bonuses here and there, so now, if you want food you have to work for it. Not enough food and your cities will stagnate. Oh, I forgot something critical. Now you need to reach city size 4 before you can even start working on a settler, and once you produce the settler, that city will lose 1 population. Both things made the early game much more longer than usual. Coveting the land is harder, both from the unhappiness upon extension and because of the lack of food, resulting in wild land filled with barbarians for longer. The global metric of unhappiness is the number of unhappiness produced divided by the number of happiness produced, expressed from 0 to 100. Don't settle any more cities if you see your happiness dropping below 100 and be cautious if you plan to conquer cities, specially in the early game, as the unhappiness is very hard to bear in annexed cities.
If you have a too wide empire, and you don't have any tool left to resist rebelion, just let one of your cities secede. That will create a city state and release you from the struggle.
A minor change, you may say, is that now the cost of progress is downgraded as a civ loses cities, so a civ that has lost many cities may still keep up in time, if it saved its better cities.
4. All those changes are things that we all agreed upon, and we didn't ask for reversal, so I'd say we're liking them. All them addressed concerns we had. I'd say it's more mature. Your's to say if you like them too.
EDIT.
Geez, I forgot other changes, combat related:
Swordsmen are gaining now Cover for free.
Fusiliers on, gain anti-mounted.
Mounted units now pay higher cost to move through rough terrain.
Aaand you should try new naval promotions. It's a whole new world.